All-fiber Quantum Logic

Photonics.comMay 2009
BRISTOL, UK, May 29, 2009 – The only quantum technology in practical use today is quantum cryptography and it is currently limited in the distance over which secure communication may occur. However, a team of physicists and engineers have now demonstrated all-fiber quantum logic, where single photons are generated and used to perform the controlled-NOT quantum logic gate in optical fibers with high fidelity.

An image of a photonic crystal fiber, courtesy of Alex Clark.
More sophisticated quantum networks will require multiple nodes with the ability to implement small-scale quantum processing in order to increase the range of quantum communications. Such networks will rely on optical fiber links, making fiber-based photon generation and information processing of key technological importance.

Jeremy O'Brien, professor of Physics and Electrical Engineering at Bristol University and colleagues, have shown it is possible for a high-fidelity fiber controlled-NOT gate to operate with fiber heralded single-photon sources.

"On the basis of a simple model we are able to conclude that imperfections are primarily due to the photon sources, meaning that the gate itself works with very high fidelity," said O’Brien. "Such all fiber quantum information processing will likely have important applications in future quantum networks."

All-fiber quantum information processing could be used in less mature quantum technologies such as computing, communication and advanced measurement, as well as in the fundamental science of quantum optics.

The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and detection by optical components and instruments, lasers and other light sources, fiber optics, electro-optical instrumentation, related hardware and electronics, and sophisticated systems. The range of applications of photonics extends from energy generation to detection to communications and...

The area of optics in which quantum theory is used to describe light in discrete units or "quanta" of energy known as photons. First observed by Albert Einstein's photoelectric effect, this particle description of light is the foundation for describing the transfer of energy (i.e. absorption and emission) in light matter interaction.